Manufacture of compound tubing.



No. 798,055. PATBNTED AUG. 22.. 1905.

' J. H. NICHOLSON.

MANUFACTURE OF COMPOUND TUBING.

APPLICATION FILED APE.25, 1904.

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NO- 798,055. v PATENTED AUG. 22, 1905. J. H. NICHOLSON,

MANUFACTUREOF COMPOUND TUBING.

APPLICATION FILED APB..25, 1904.

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UNITED STATES PATENT OFFICE.

JOHN H. NICHOLSON, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO NATIONAL TUBECOMPANY, OF PITTSBURG, PENNSYLVANIA, A

CORPORATION OF NEW JERSEY.

Specification of Letters Patent.

Patented Aug. 22, 1905.

Application filed April 25, 1904. Serial No. 204,704..

To all whom it may concern:

Be it known that I, JOHN H. NIoHoLsoN, of Pittsburg, Allegheny county,Pennsylvania, have invented a new and useful Improvement in theManufacture of Compound Tubing, of which the following is a full, clear,and exact description, reference being had to the accompanying drawings,forming part of this specification, in which- Figurel is a sectionalplan view showing the step of welding a thin heated nickel tube to aheated pierced billet. Figs. 2 and 3 are views showing the reducing andelongating of the compound hollow billet. Fig. 4: is a plan view similarto Fig. 1, showing the welding of an exterior cover to the piercedbillet; and Fig. 5 shows another means of welding the exterior covering.

My invention relates to the manufacture of compound tubing having aninside or outside covering.

The invention relates particularly to the welding of a nickel covering,either external or internal, or both, to a steel or iron tube in orderto give a non-corrosive surface, and is designed to provide a processwhereby the surfaces may be thoroughly welded, so that when the tube isbent, expanded, or otherwise changed in form there will be no separationbetween the layers.

' Iron and steel tubes have beencoated by dipping in zinc, tin, lead,&c., and have also been electroplated with copper, nickel, &c. Thiselectroplating can be carried out successfully in giving an exteriorcoating; but it is very difficult to electroplate the interior of thetube. Where this coating is of considerable thickness, theelectroplating of metal is irregular, porous, and brittle, and themetals are liable to separate when the tube is beaded or manipulated. Ithas also been proposed to weld a copper or brass lining in iron or steeltubes; but the melting-points of the two metals are so dissimilar thatwhen this is attempted the copper or brass lining or covering will meltand run before the iron or steel reaches the welding temperature. Hencethere is no substantial weld between the metals in this case, and whenthe tube is changed in form the metals will separate.

I have discovered that I can successfully weld a layer of nickel to aniron or steel tube either externally or internally by protecting thewelding surfaces from oxidizing influences while heating the nestedblank, and that by applying pressure a substantial and perfect weld isobtained. Nickel is well adapted to withstand corrosion and oxidation atordinary temperatures. Itis of about equal hardness with steel, and thefusing-points o the two metals are near each other. I

In attempting to weld nickel-to iron by ordinary methods the-nickel whenheated absorbs oxygen, which changes the nature of the welding surfaceand prevents a proper welding; but by nesting the two hollow blanks ofnickel and iron within each other and protecting their welding surfaceswhile heating I can obtain excellent results.

In carrying out my invention for the manu facture of a nickel-linedboiler-tube I preferably take a pierced steel billet that has had itsinterior surface pickled or cleaned, so as to remove all scale or oxiol,and nest within it a thin nickel tube of the same length as the piercedbillet. I then drive tapering plugs into the ends of the nickel tube,expanding the same so that they fit snugly into the ends of the hollowbillet and prevent the air and hot gases of the furnace from coming incontact with the welding surfaces of the nickel and steel to any harmfulextent. .I then place this compound hollow billet or blank in a furnaceand heat it to, preferably, about 2,200 to 2,300 Fahrenheit. When theblank is thoroughly heated to this temperature, it is withdrawn from thefurnace and passed through angularly-disposed rotating rolls or disksand over an interior supporting-mandrel, giving it a high rotary speedand at the same time a forward motion over the mandrel, subjecting allportions of the billet to a great pressure,reducing the thickness ofwall, and elongating the billet. For this operation 1 preferably use theapparatus of United States Patent N 0. 718,723, dated January 20,

1903, as shown in Fig. 1, the compound blank welded blank thus formed isthen placed on a mandrel 5 and at the same heat is reduced in diameterand thickness and elongated by the well-known swaging process used inmaking seamless steel tubes. This step of the process is illustrated inFig. 2, in which the swagingrolls are shown at 6 and 7. The hot rolledtube as it comes from the swaging-mill can be further reduced indiameter and thickness of wall, if so desired, by the usual method ofcold-drawing, as well understood by those versed in the art. In thisstep the wall thickness of the nickel and the steel is reducedproportionately and the compound tube draws like one solid piece ofmetal, the weld being so perfect that the line of union of the twometals cannot be detected without etching with acid, the color of thenickel and steel being alike.

In Fig. 4: I show the welding of an exterior covering to the piercedbillet. This operation of welding is identical with that of welding theinterior lining,excepting that the thin nickel tube is on the outsideinstead of the inside of the steel blank.

In Fig. 5 I show another means of welding an outside covering onto apierced blank by passing the composite hollow billet through circulargrooved rolls 8 and 9 of the bar-mill type and over an interiorsupporting mandrelplug 10, the composite billet having been prepared andheated similarly to the operation described for producing lined tubing,excepting that the thin nickel tube is placed on the outside of thepierced blank. After the first pass over the mandrel-plug this coveredusual method of manufacturing seamless.

tubes. No new apparatus of any kind is required, as the cross-rollingdevice used for securing the weld is the same as is used for theproduction of the pierced steel billets, and the subsequent rollingdevices for elongating the welded blank are the same as used for makingthe seamless steel tubes. The nickel tubes for lining and covering aremade in an identical manner as the steel tubes. The only difference inmaking the steel tubes and the nickel lining-tubes is the duplicating ofseveral of the different operations. The article produced is of highquality, as the weld is substantially perfect throughout and themetalswill not separate when the tube is beaded or otherwise changed in form.Although the nickel may be much less malleable than the steel, thecompound tube can'be subjected without injury to substantially the sametreatment as a tube of steel.

The protecting of the welding surfaces of the hollow blanks is of greatimportance, as it enables me to obtain the complete weld between theblanks. The small amount of air between the blanks does not preventtheir welding, and during the heating the inner finished nickel blankexpands, thus bringing the welding surfaces closer together.

The invention may be used for the welding of steel or iron to an alloyof nickel, the same being nested and treated as before described. It mayalso be used for welding other dissimilar metals or alloys the surfacesof which cannot be welded by ordinary methods on account of theoxidizing or change in the nature of the welding surfaces due to contactwith the hot gases of the furnace. Instead of expanding the ends of thethin tube the tubes may be nested together so closely as to practicallyexclude the oxidizinggases. I may also take the pierced billet as itcomes in its heated condition from the'piercing-mill, before it has hadtime to materially oxidize on its inner surfaces, and slip thelining-tube Within it and then pass the compound blank through acircular rolling-mill pass, which will roll the pierced steel blank downonto the lining-tube. This will prevent the oxidizing of the Weldedsurfaces during the heating 7 of the compound blank.

In appplying the external cover to the pierced blank I may heat thecover, slip it on the hot pierced blank before scale has formed on itsexterior, and then pass the blank through a circular rolling-mill pass,thus bringing the surfaces closely together and preventing the oxidizingaction. so that both surfaces are in excellent shape.

The apparatus employed may be changed, and many other changes may bemade without departing from my invention.

I claim- 1. The method of making a compound tube comprising an iron orsteel body and a nickel tube welded thereto, consisting in compressingand welding a hollow iron or steel blank and a tube of nickel alloywhile said blank and tube are heated to a welding temperature, theadjacent surfaces of said blank and tube being protected from oxidation;substantially as described.

2. The method of making a compound tube comprising an iron or steel bodyand a seamless nickel tube welded thereto, consisting in compressing andWelding a hollow iron or steel blank and a seamless tube of nickel alloywhile said blank and tube are heated to a welding temperature, theadjacent surfaces of said blank and tube being protected from oxidation;substantially as described.

3. The method of making compound tubing, consisting in nesting togethera heavy-walled hollow steel blank and a thin-walled tube of nickel ornickel alloy closing at the end the intermediate space between saidtubes to exclude oxidizing-gases, heating the compound blank andcompressing and welding it over an internal support and between rolls;substantially as described.

In testimony whereof I have hereunto set my hand.

JOHN H. NICHOLSON.

Witnesses:

GEO. B. BLEMING, JOHN MILLER.

